Recitation Assignment 3

Due at the end of class

 Recitation Problem:

    You are scuba-diving in a karstic cave system near a landfill and you come across a large,

        trapped air bubble. You sample the bubble with your portable gas chromatograph    

        and find that the bubble contains benzene at a partial pressure of 0.12 atm (benzene: C₆H₆ is

        a common carcinogenic organic pollutant). Assume STP (i.e. Temperature is 25 deg C and 

        total pressure in the bubble is 1 atm.

         K_H for benzene is 5.5 atm*L*mol^-1 at 25 deg C

(a)   What is the concentration of benzene in the bubble in ppmv?

(b)  Assuming the bubble is in equilibrium with the water,

       what is the concentration in mg/l of benzene in the cave water?

(c)  How does this compare to the MCL (EPA maximum concentration levels

        for drinking water)  MCL for benzene is 5 µg/l?

Problem adapted from Appelo, C.A., Postma, D., (2005), p.